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    <b>加粗</b>  <br>

    <strong>加粗-语义方面强调</strong>    <br>

    <i>斜体</i>  <br>

    <em>斜体-语义</em>  <br>

    <u>下划线</u>  <br>

    <del>贯穿线，删除线</del> <br>

    O<sub>2</sub>  <br>

    3<sup>4</sup> <br>

    &copy;  <br>

    &reg; <br>

    空&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;格

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